According to ABC News, 46-year-old Brown received a transplant of blood stem cells to treat leukemia in 2007, and now his body shows no signs of the virus, making him the world's sole victor over AIDS. And while he is a special case, doctors hope to repeat the procedure used on Brown for others.

Brown got lucky. The blood stem cells he received came from a donor with a special genetic mutation that made him resistant to HIV. The genetic mutation occurs in less than 1 percent of Caucasians, and far less frequently in people of other races. Before Brown got his transplant in 2007, doctors tested nearly 70 donors for this genetic mutation before they found one who was a match. But doctors hope that a similar solution could help other people with HIV: umbilical cord blood transplants.

Dr. Lawrence Petz, medical director of StemCyte, an umbilical cord blood bank, said although Brown was cured by his transplant, the process was complicated because the blood stem cells came from an adult donor.“When you do that you have to have a very close match between donor and recipient,” Petz said. “With umbilical cord blood, we don't need such a close match. It's far easier to find donor matches.”